1. Field of the Invention
This invention relates to a method for cleaning debris and, more particularly, to a method which allows a desired substance to be obtained from the debris.
2. Background Information
It is, frequently, desirable to excavate debris, clean it and obtain desired substances during the cleaning process. As interest in the land grows, governmental agencies continuously issue more and more stringent standards concerning material, such as debris, which contain substances that may be harmful if not removed. As a result, industries which had, heretofore, only provided primary services to remove certain substances are now faced with the necessity of providing additional services to remove even more substances from debris. Additionally, certain industries are often faced with the burden of paying surcharges for inadequately removing substances from debris.
While some debris cleaning equipment provides adequate performance, some are expensive to install and operate. Further, some units take a long period of time to process the debris and result in a low volume/time yield of desired substances which are to be obtained. With the interest in protecting the land continuing to increase along with the interest in increasing the efficiency in land-related processes, certain specialists are constantly striving to obtain more efficient and less costly methods for the cleaning of debris. Such efficient techniques are especially important due to the increased use of substances which may affect the land.
Accordingly, this invention relates to a process for extracting heavy metals and organic chemicals from polluted substances and, more particularly, to such a process wherein the extracted heavy metals are, generally, water free.
Polluted soils, slurries and dusts, in addition to inert substances such as sand, humus, brickbat, gravel and wood, frequently contains heavy metals, heavy metal salts and/or heavy metal oxides.
It has been known to eliminate heavy metals from these soils, slurries or substances by treating them with aqueous, diluted inorganic or organic acids. In such a process, which may be performed by leaching, the percentage of water in the acid solutions employed is between 20% and 95%. The water portion, however, is an undersireable portion or solvent, which has to be removed in order to obtain the desirable water-free metal salts. When using, for example, an aqueous acetic acid or other organic acid, the water leads to the formation of muddy or slimy products or residues. The latter are formed by the oil present in the polluted soils or slurries.
Because of that, the separation of the metal salts, that are in the form of acetates, is more difficult. These metal salts contain an oil slurry impurity. Therefore, to enable further use of the metal salts, through recycling, an additional purification procedure is necessary to make them reusable.